everyday I thank juyeon for saving humanity by keeping this rabid dog off the streets

Does that mean that jiwook actually hurt others too? Not just juhyeon?

That is I been SAYING

Not sure about that but Jiwook was a raging bully + had extreme anger issues to the point everyone around him was scared of him. Even in the first chapter he was making crude jokes about raping juyeon with his only friend. Personally I think thats enough reason to not want him roaming freely on the streets.